Satellite communication ranging

ABSTRACT

A telecommunications system includes a plurality of ranging terminals programmed to communicate with a plurality of satellites over a plurality of frequencies. A processor, having a memory, is programmed to receive ranging data from each of the plurality of ranging terminals, determine a plurality of power levels for each of the plurality of terminals, and transmit the plurality of power levels to each of the plurality of ranging terminals. Each power level is associated with one of the plurality of frequencies. The plurality of ranging terminals is programmed to transmit signals to the plurality of satellites over the plurality of frequencies in accordance with the power levels determined by the processor.

BACKGROUND

In certain existing satellite communication systems, the satelliteterminal, during its initial installation and commissioning, performs aprocedure, subsequently referred to as a ranging procedure, to determinethe nominal transmit power setting for the uplink transmission. Thisnominal transmit power depends on the nominal value of end-to-endchannel gain and the total noise plus interference level (the greaterthe channel gain, the lesser the required transmit power. On thecontrary, the greater the noise and interference, the greater therequired transmit power).

During the ranging, the satellite terminal transmits the ranging signalat one frequency. Based on a received power level or Signal to NoiseRatio (SNR) level of the ranging signal received at the satellitegateway, the satellite terminal determines a nominal transmit powerlevel.

In certain existing satellite communication systems, spectral density,or level, of noise plus interference is assumed to be identical acrossall frequencies. The certain existing satellite communication systemsassume that the spectral density is flat across all inroute frequencies.As a result, the nominal transmit power level estimated at the rangingfrequency is used with respect to other inroute frequencies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example telecommunications system with multiplesatellites in communication with multiple terminals over multiplefrequencies.

FIG. 2 is a block diagram showing example components of one of theterminals.

FIG. 3 is an example sample puncturing pattern 300 that illustrateswhich terminals performed ranging processes at particular frequencies.

FIG. 4 illustrates a relationship between various matrices directed tomeasured range data, interference floor values, and terminal offsetvalues.

FIG. 5 is a flowchart of an example process that may be executed by aprocessor incorporated into the telecommunications system of FIG. 1.

DETAILED DESCRIPTION

In some satellite communication networks, the satellite gateway (GW)outroute transmissions (i.e., transmission from the GW to the userterminals via the satellite) can interfere with inroute transmissions(i.e., transmission from the user terminals to the GW via thesatellite). The inroute transmissions from the user terminal areaffected by thermal noise effects. In addition, the presence of outrouteinterference results in an increase in the spectral floor due toimpairments. The level of the interference can vary with varying centerfrequencies and bandwidths of the outroute signals. This interferenceaffecting a given inroute frequency typically does not varysignificantly over time.

Due to variation of noise and interference floor, it may be necessary toperform multi-frequency ranging in which the ranging is performed atmore than one inroute frequencies by a given terminal.

As the ranging process, especially when performed at more than oneinroute frequency, is time consuming and satellite link resourceconsuming, it is beneficial if not all the terminals are required toperform the multi-frequency ranging. To meet this objective, thesatellite Gateway determines the variation of the interference flooracross different inroute frequencies. Subsequently, Gateway broadcasts atable containing this frequency-dependent interference floor variationon the outroute. A terminal that receives this information on theoutroute needs to perform only the conventional, single-frequency,ranging; it can use the broadcast interference table to determine thetransmit power level for the rest of the inroutes. This disclosureproposes a method using which the Gateway can determine the variation ofthe interference floor across different inroute frequencies.

Two-fold challenges in this estimation problem are as follows: (i) acertain limited number of terminals perform the multi-frequency ranging(the rest use the single-frequency ranging combined with theinterference floor table broadcast from the GW). Multi-frequency rangingprocess at each of the terminals is affected by a terminal-specificperturbation, which arises because of the satellite beam gain variationat different locations of these terminals, satellite channel gainvariations (e.g., due to weather) at these terminals, terminal hardwarespecific variations, etc. (ii) Furthermore, to reduce the overhead dueto multi-frequency ranging, each of the terminal that performs thisprocess ranges only a small subset of the entire set of inroutefrequencies. This subset is also terminal-specific; different terminalsmay range on different subsets of inroute frequencies. Due to (i) and(ii) above, the collection of measurements obtained by differentterminals at the end of multi-frequency ranging form a partialoverlapping subsets of measurements, where each subset is affected by adifferent unknown random variable.

The task at the Gateway of determining a single table containing theinterference floor variations across inroutes using these multipleoverlapping subsets of ranging measurements is solved by the presentdisclosure. Alternative/prior approaches that address this concern are(i) a locked reference method, and (ii) a floating reference method. Inthe locked reference method, ranging occurs at a particular frequencythat is ideally the same for all terminals. This way, terminal locationdependent and/or terminal hardware-specific measurement offsets (thataffect and impair the estimation of the system-wide static interferencefloor) can be detected and compensated for. In the floating referencemethod, different terminals may perform the ranging at differentfrequencies, which allows for more flexibility during ranging. In thismethod, the terminal location dependent and/or terminalhardware-specific differences are compensated for by designating themeasurements from certain terminals which are collected with a strongsignal quality as the reference.

While the locked reference and floating reference methods, discussedabove, can provide adequate estimates of appropriate power levels, thosemethods suffer from certain drawbacks. For instance, both areheuristically applied and are ad-hoc in nature. They may both discarddata which increases the amount of variance in their respective powerestimations. Finally, both these methods require certain system levelassumptions that can constrain the flexibility in the terminal-drivenranging process. In a scenario in which these assumptions are not met,these methods may fail to provide the desired estimates of thefrequency-specific interference floor levels.

One alternative approach is an optimized linear estimator model,described in greater detail below. When applied to a telecommunicationssystem, the optimized linear estimator model is implemented via aprocessor executing instructions stored in a memory. The instructionsinclude receiving ranging data from multiple ranging terminals,determining power levels for each terminal, and transmitting the powerlevels to the terminals. Each power level is associated with at leastone frequency. The ranging terminals are programmed to transmit signalsto the satellites in accordance with the power levels for each frequencydetermined by the processor.

Development of the optimized linear estimator model may rely on variousparameters including, e.g., the number of inroute frequencies N, thenumber of terminals M that perform controlled ranging, A parameter c_(n)that represents the interference floor affecting n^(th) inroute as nvaries from 1 to N, the terminal specific offset k_(m) present in them^(th) terminal's ranging data as m varies from 1 to M, and the rangingdata r_(m,n) measured on the n^(th) inroute by the m^(th) terminal. Onerelationship between these parameters is shown below in Equation (1).r _(m,n) =c _(n) +k _(m) +u _(m,n)  (1)where the expression u_(m,n) represents the noise affecting themeasurement of n-th inroute at m-th terminal.

The ranging data r_(m,n) in Equation 1 is the normalized ranging powerrequired to achieve the target energy per symbol to noise power spectraldensity (E_(s)/N_(o)). This is modeled as the sum of the parameter ofinterest c_(n), a terminal-specific nuisance parameter k_(m), and themeasurement noise u_(m,n), all in decibels. Note that the parameterk_(m) accounts for the variations from terminal to terminal (indexed bym) in the path loss, the return beam contour level, and (e.g.,weather-induced) shadowing and fading.

The ranging process obtains the measurement r_(m,n) in a sparse manner;i.e., r_(m,n) is not obtained for all pairs of inroutes (m) andterminals (n), an example of which is shown in FIG. 3. The data (i.e.,the r_(m,n) values) from multiple terminals can be aggregated into amatrix R, whose rows equal the number of inroutes and columns equal thenumber of terminals. A vectorial form r of matrix R is shown in FIG. 4.This vector r is obtained by stacking rows of R and taking the transposeof the stacked rows. Also shown and discussed below with regard to FIG.4 is the vector d, which includes various unknowns associated with eachranging. An adjacency matrix A and a diagonal matrix W, examples of bothof which are also shown in FIG. 4, are used to determine the values ofthe unknowns shown in vector d.

The adjacency matrix A may be sparsely populated. Any row of A may haveonly two nonzero unit-valued entries that define the adjacency betweenthe corresponding c and d parameters. The diagonal matrix W is a matrixof confidence metrics corresponding to the measurement vector r. If anelement of the measurement vector r is trustworthy, the correspondingdiagonal element of matrix W is set to be near unity. If an element of ris unavailable, corresponding diagonal element of W is set to zero. Ingeneral, diagonal elements of W are set in a range from 0 to 1 and aremade proportional to the reliability or quality of the correspondingelement of vector r. In further generality, matrix W can be madenon-diagonal and set to the covariance of the measurement noise, ifavailable.

The unknown vector d and the measurements r are related by the adjacencymatrix A. The columns of the adjacency matrix A are not independent.Removing one of N different k parameters shortens the unknown vector dby one element and removes the corresponding column of the adjacencymatrix A. This shortened matrix equation can be represented as shown inEquation (2).r _((N×M)×1) =A _((N×M)×(N+M−1)×1) ×d _((N+M−1)×1)  (2)Although the nomenclature has not changed, the number of columns of theadjacency matrix A has been reduced by one, as has the number ofelements of the unknown vector d. Thus, the measured ranging data can berepresented by the following simplified equation:r=A×d  (3)

Given Equation (3), the unknown vector d can be determined with a givenmeasurement matrix r. That is, if the adjacency matrix A is aninvertible square matrix, the solution may be obtained by multiplyingthe inverse of the adjacency matrix A with the measurement matrix r.However, in general, the adjacency matrix A is a rectangularnon-invertible matrix. Therefore, one solution is to use a WeightedLeast Squares approach.

The Weighted Least Squares estimate of the unknown vector d may berepresented as follows:{circumflex over (d)}=(A ^(T) WA)⁻¹ A ^(T) Wr  (4)The first N elements of the estimated vector {circumflex over (d)} aboverepresent the estimated c parameters. The remaining M−1 elementsrepresent estimates of the terminal-specific k parameters. Theterminal-specific k parameters can be used to derive the statues of,e.g., weather conditions at the terminal at the time the rangingoccurred.

The disclosed optimal linear estimator model incorporates all rangingmeasurements, which reduces ambiguity. Moreover, it compensates forissues such as weather conditions at different terminals since itseparately captures the k parameter, which captures the terminalspecific perturbations that affect measurement of all inroutes at agiven terminal. The modeled parameter k, however, may not captureconditions in which the terminal's ranging is affected by the weather ona few, but not all, inroutes. In such instances, a rain fade flag, forinstance, can be used to discard such measurements if necessary ordesired.

The elements shown in the Figures may take many different forms andinclude multiple and/or alternate components and facilities. The examplecomponents illustrated are not intended to be limiting. Indeed,additional or alternative components and/or implementations may be used.Further, the elements shown are not necessarily drawn to scale unlessexplicitly stated as such.

Referring now to FIG. 1, the telecommunications system 100 includesmultiple ranging terminals 105, multiple satellites 110, and a rangingprocessor 115.

The ranging terminals 105 include hardware components that facilitatecommunication with the satellites 110 over a number of differentfrequencies, also referred to as inroutes. Some components of theterminal are shown in and discussed with reference to FIG. 2. Ingeneral, the ranging terminal 105 may transmit signals to, and receivesignals from, various satellites 110. The ranging terminals 105 may eachbe programmed to range on the various satellites 110 at variousfrequencies. During the ranging, the ranging terminals 105 may collectranging data on multiple inroutes. The ranging terminals 105 areprogrammed to output the ranging data to the ranging processor 115.Moreover, the ranging terminals 105 are programmed to receive commandsignals, from the ranging processor 115, that command the rangingterminals 105 to communicate with the satellites 110 at power levelsdetermined by the ranging processor 115 based on the ranging data.

The satellites 110 include hardware components that facilitatecommunication with the ranging terminals 105. The satellites 110 areprogrammed to communicate with the ranging terminals 105, includingparticipating in the ranging process executed by the ranging terminals105. The satellites 110 may be in the Earth's orbit. Example orbitsinclude a geostationary orbit, low Earth orbit, or the like. Thesatellites 110 may each be programmed to transmit signals at variousfrequencies to various ranging terminals 105.

The ranging processor 115 includes circuits and other hardwarecomponents that receive and process the ranging data generated by theranging terminals 105. In some possible approaches, the rangingprocessor 115 is incorporated into a Gateway. The ranging processor 115is programmed to receive the ranging data from the ranging terminals105, determine various power levels for each ranging terminal 105 andfor each inroute frequency, and transmit the power levels to the rangingterminals 105 with a command for the ranging terminal 105 to communicatewith the satellite 110 according to the determined power levels. Thepower levels may be specific to particular ranging terminals 105, targetsatellites 110, and frequencies. Thus, the power level for one rangingterminal 105 to communicate with a particular satellite 110 may bedifferent from the power level for a different ranging terminal 105 tocommunicate with the same satellite 110. Further, the power level for aranging terminal 105 to communicate with one satellite 110 may bedifferent from the power level for that same ranging terminal 105 tocommunicate with a different satellite 110. In another example, thepower level for a ranging terminal 105 to communicate with a satellite110 over one inroute frequency may be different than the power level forthe same ranging terminal 105 to communicate with the same satellite 110but over a different inroute frequency.

The ranging processor 115 is programmed to consider various ranging datato develop the power levels. The ranging processor 115, for instance, isprogrammed to estimate the interference floor values and the terminaloffset values. The ranging processor 115 may be programmed to aggregatethe interference floor values, and the terminal offset values furtherdiscussed below with reference to FIG. 4. The ranging processor 115 isprogrammed to determine the measured range data according to thoseaggregated values, and the power levels from the measured range data.

The ranging processor 115 may incorporate a memory 120, which ishardware for electronically storing data. The memory 120 may store,e.g., ranging data, power levels, or both. Moreover, the memory 120 maystore instructions executable by the ranging processor 115. Theinstructions may include the instructions executed by the rangingprocessor 115 associated with receiving and processing the ranging data,determining the power levels, and commanding the terminals tocommunicate in accordance with the determined power levels.

FIG. 2 illustrates example components of a ranging terminal 105. Asshown, the example components include a transmitter 125, an antenna 130,and a terminal processor 135.

The transmitter 125 may be implemented via hardware circuits or otherhardware components that generate signals to be transmitted to one ormore satellites 110. For instance, the transmitter 125 may generatesignals at various frequencies that can be transmitted to the satellites110. The signals may be generated in accordance with commands receivedform the processor. The commands may identify particular power levelsfor the particular frequency and target satellite 110. Thus, theterminal is programmed to generate the signals according to the powerlevel commanded by the processor. The signals generated by thetransmitter 125 may be output to the antenna 130.

The antenna 130 may include hardware that can be used to broadcastsignals, generated by the transmitter 125, to the satellites 110. Forinstance, the antenna 130 may include hardware that converts signalsreceived from the transmitter 125 into radio waves at particularfrequencies. The antenna 130 broadcasts the signals to the satellites110 at the power levels commanded by the processor.

The terminal processor 135 includes circuits and other hardwarecomponents that control operation of the transmitter 125, the antenna130, or both. The terminal processor 135 may include a terminal memory140 that can electronically store data associated with, e.g., the powerlevels determined by the ranging processor 115 and instructions for thetransmitter 125 and antenna 130 to transmit signals according to thepower levels determined by the processor. The terminal processor 135 mayaccess data stored in the terminal memory 140 and output signals,including commands, to the transmitter 125 to generate signals accordingto the power levels determined by the ranging processor 115.

FIG. 3 is an example sample puncturing pattern 300 that illustrateswhich terminals performed ranging processes at particular frequencies.Each white space indicates that the ranging process was performed. Eachblack space indicates that the ranging process was not performed at thatterminal on the given inroute. As shown in FIG. 3, the terminalidentified by index number 1 ranged on inroute frequencies 3, 6, 9-13,and 15. The terminal identified by index number 6 ranged on inroutefrequencies 1-6, 9-10, 14, and 16. A row with all white blocks wouldindicate that a particular terminal ranged on all inroute frequencies. Acolumn with all white blocks would indicate that all terminals ranged ona particular inroute frequency. Conversely, a row with all black blockswould indicate that a particular terminal has not ranged on any in routefrequencies. A column with all black blocks would indicate that none ofthe terminals ranged on a particular inroute frequency.

None of the rows and columns shown in FIG. 3 are completely filled withwhite or black blocks, indicating that some ranging data is availablefor each terminal and each inroute frequency. The collected ranging datacan be used to determine power levels for each terminal at each inroutefrequency. For instance, the ranging data for each terminal can beprocessed to determine, e.g., the terminal-specific offset value k_(n)and the parameter c_(m) of interest that models the inroute-specificinterference floor. Thus, by way of example, even though only threeterminals (i.e., the terminals with index numbers 6, 7, and 9) haveranged on inroute frequency 1, and their ranging process measurementswere affected by different terminal-specific offsets values(specifically, k₆, k₇ and k₉), although these three ranging measurementsare not directly useable (due to presence of these offsets), enoughinformation may be available from the entire set of measurements(represented by the white cells) to determine and separate theinterference floor values c_(m) that affect different inroutefrequencies from the terminal-specific offset values that may haveaffected the ranging processes performed by different terminals.

FIG. 4 illustrates a relationship between various matrices used tocollect the measured ranged data, interference floor values, and theterminal offset values at different inroute frequencies. For instance,the ranging data, such as the ranging data collected in concert withgenerating the puncturing pattern 300 of FIG. 3, can be represented inthe various matrices shown in FIG. 4. Three vectorial representationsare shown in FIG. 4. The vectorial representations are based on theterms of Equation (2), discussed above, where the vector r representsthe ranging data and the vector d represents various unknowninterference floor values (i.e., the c parameter discussed above) andunknown terminal offset values (i.e., the k parameter discussed above).The adjacency matrix A, as discussed previously, relates the unknownvector d to the ranging data r. Thus, with respect to Equation (4)above, the unknown vector d can be solved for using, e.g., a weightedleast squares technique. Specifically, the unknown c parameters and kparameters can be determined. With all of the unknowns addressed, thepower levels for each of the terminals communicating at each inroutefrequency can be determined and applied.

FIG. 5 is a flowchart of an example process 500 that may be executed bythe ranging processor 115. The process 500 may be executed at any timeafter at least some of the terminals have ranged on at least some of thefrequencies. The process 500 may be executed once initially to providepower levels to each terminal, and then repeated occasionally as moreterminals have had the occasion to range on more frequencies. Thus, theprocess 500 may be repeated as additional ranging data becomes known.

At block 505, the ranging processor 115 receives ranging data from theterminals. The ranging data is affected by the interference floorvalues, terminal offset values, measured noise, etc. Further, theranging data may further include other information such as anidentification of the terminal from which the data originated, theparticular inroute frequencies ranged upon, the date and time of theranging, the weather conditions associated with the ranging, or thelike.

At block 510, the ranging processor 115 aggregates the ranging datareceived from each terminal. Aggregating the data may includeaggregating known interference floor values, aggregating known terminaloffset values, aggregating known noise values, etc. For instance,aggregating the ranging data may include generating a puncturing patternsuch as the example one shown in FIG. 3, parts of the matrix shown inFIG. 4, including the values shown in the vector r and the adjacencymatrix A, or both.

At block 515, the ranging processor 115 determines the relativeinterference floor levels for different inroute frequencies. Determiningthe interference levels may include determining the values of theunknown vector d using, e.g., a weighted least squares function such asthat shown and discussed above with respect to Equation (4). In otherwords, the ranging processor 115 may use to extract, from the datacollected during actual ranging processes performed by the variousterminals, the unknown interference floor values (e.g., the c parametersin the adjacency matrix A) and the unknown terminal offset values (e.g.,the k parameters in the adjacency matrix A). The estimated c parametervalues can be used to determine the power levels for each terminal tocommunicate over each inroute frequency even though each terminal maynot have ranged on each inroute frequency.

At block 520, the ranging processor 115 transmits the power levels toeach of the terminals. This way, the ranging processor 115 cancommunicate the particular power levels that each terminal should applydepending on the inroute frequency used to communicate with a particularsatellite 110. The terminals may operate according to the power levelsdetermined by the ranging processor 115.

The process 500 may repeat at various intervals or in response tovarious events, such as when a change is made to the telecommunicationsystem. Examples of events may include adding, removing, or replacing asatellite 110, adding, removing, or replacing a terminal, communicatingover different inroute frequencies, a terminal ranges on a differentinroute frequency, or the like. By periodically repeating the process500, the power levels may be continually updated. Moreover, because thepower levels are based on a process that considers the entirety ofmeasurements collected during actual ranging processes performed by thevarious terminals (no data is discarded from each ranging processperformed), the process 500 estimates power levels that are most likelyto be successful.

In general, the computing systems and/or devices described may employany of a number of computer operating systems, including, but by nomeans limited to, versions and/or varieties of the Microsoft Windows®operating system, the Unix operating system (e.g., the Solaris®operating system distributed by Oracle Corporation of Redwood Shores,Calif.), the AIX UNIX operating system distributed by InternationalBusiness Machines of Armonk, N.Y., the Linux operating system, the MacOSX and iOS operating systems distributed by Apple Inc. of Cupertino,Calif., the BlackBerry OS distributed by Blackberry, Ltd. of Waterloo,Canada, and the Android operating system developed by Google, Inc. andthe Open Handset Alliance. Examples of computing devices include,without limitation, a computer workstation, a server, a desktop,notebook, laptop, or handheld computer, or some other computing systemand/or device.

Computing devices generally include computer-executable instructions,where the instructions may be executable by one or more computingdevices such as those listed above. Computer-executable instructions maybe compiled or interpreted from computer programs created using avariety of programming languages and/or technologies, including, withoutlimitation, and either alone or in combination, Java™, C, C++, VisualBasic, Java Script, Perl, etc. Some of these applications may becompiled and executed on a virtual machine, such as the Java VirtualMachine, the Dalvik virtual machine, or the like. In general, aprocessor (e.g., a microprocessor) receives instructions, e.g., from amemory, a computer-readable medium, etc., and executes theseinstructions, thereby performing one or more processes, including one ormore of the processes described herein. Such instructions and other datamay be stored and transmitted using a variety of computer-readablemedia.

A computer-readable medium (also referred to as a processor-readablemedium) includes any non-transitory (e.g., tangible) medium thatparticipates in providing data (e.g., instructions) that may be read bya computer (e.g., by a processor of a computer). Such a medium may takemany forms, including, but not limited to, non-volatile media andvolatile media. Non-volatile media may include, for example, optical ormagnetic disks and other persistent memory. Volatile media may include,for example, dynamic random access memory (DRAM), which typicallyconstitutes a main memory. Such instructions may be transmitted by oneor more transmission media, including coaxial cables, copper wire andfiber optics, including the wires that comprise a system bus coupled toa processor of a computer. Common forms of computer-readable mediainclude, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, any other magnetic medium, a CD-ROM, DVD, any otheroptical medium, punch cards, paper tape, any other physical medium withpatterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any othermemory chip or cartridge, or any other medium from which a computer canread.

Databases, data repositories or other data stores described herein mayinclude various kinds of mechanisms for storing, accessing, andretrieving various kinds of data, including a hierarchical database, aset of files in a file system, an application database in a proprietaryformat, a relational database management system (RDBMS), etc. Each suchdata store is generally included within a computing device employing acomputer operating system such as one of those mentioned above, and areaccessed via a network in any one or more of a variety of manners. Afile system may be accessible from a computer operating system, and mayinclude files stored in various formats. An RDBMS generally employs theStructured Query Language (SQL) in addition to a language for creating,storing, editing, and executing stored procedures, such as the PL/SQLlanguage mentioned above.

In some examples, system elements may be implemented ascomputer-readable instructions (e.g., software) on one or more computingdevices (e.g., servers, personal computers, etc.), stored on computerreadable media associated therewith (e.g., disks, memories, etc.). Acomputer program product may comprise such instructions stored oncomputer readable media for carrying out the functions described herein.

With regard to the processes, systems, methods, heuristics, etc.described herein, it should be understood that, although the steps ofsuch processes, etc. have been described as occurring according to acertain ordered sequence, such processes could be practiced with thedescribed steps performed in an order other than the order describedherein. It further should be understood that certain steps could beperformed simultaneously, that other steps could be added, or thatcertain steps described herein could be omitted. In other words, thedescriptions of processes herein are provided for the purpose ofillustrating certain embodiments, and should in no way be construed soas to limit the claims.

Accordingly, it is to be understood that the above description isintended to be illustrative and not restrictive. Many embodiments andapplications other than the examples provided would be apparent uponreading the above description. The scope should be determined, not withreference to the above description, but should instead be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled. It is anticipated andintended that future developments will occur in the technologiesdiscussed herein, and that the disclosed systems and methods will beincorporated into such future embodiments. In sum, it should beunderstood that the application is capable of modification andvariation.

All terms used in the claims are intended to be given their ordinarymeanings as understood by those knowledgeable in the technologiesdescribed herein unless an explicit indication to the contrary is madeherein. In particular, use of the singular articles such as “a,” “the,”“said,” etc. should be read to recite one or more of the indicatedelements unless a claim recites an explicit limitation to the contrary.

The Abstract is provided to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin various embodiments for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separately claimed subject matter.

The invention claimed is:
 1. A telecommunications system comprising: afirst ranging terminal and a second ranging terminal, each programmed tocommunicate with a plurality of satellites over a plurality offrequencies, wherein the first ranging terminal is programmed to performa ranging process at a first frequency and wherein the second rangingterminal is programmed to perform a ranging process at a secondfrequency; and a processor having a memory and programmed to receiveranging data from each of the ranging terminals, determine a first powerlevel for the first ranging terminal operating at the second frequencybased on the ranging process performed by the second ranging terminaland determine a second power level for the second ranging terminaloperating at the first frequency based on the ranging process performedby the first ranging terminal, and transmit the first power level to thefirst ranging terminal and the second power level to the second rangingterminal, wherein the first ranging terminal is programmed to transmitsignals to the plurality of satellites in accordance with the firstpower level when the first ranging terminal is operating at the secondfrequency and wherein the second ranging terminal is programmed totransmit signals to the plurality of satellites in accordance with thesecond power level when the second ranging terminal is operating at thefirst frequency.
 2. The telecommunication system of claim 1, wherein theranging data received from each of the ranging terminals is affected byan interference floor value associated with one of the plurality offrequencies.
 3. The telecommunication system of claim 2, wherein theranging data received from each of the ranging terminals is affected bya terminal offset value associated with one of the ranging terminals. 4.The telecommunication system of claim 3, wherein the processor isprogrammed to aggregate the interference floor values and terminaloffset values received from each of the ranging terminals.
 5. Thetelecommunication system of claim 4, wherein the processor is programmedto determine, using the measured range data, the aggregated interferencefloor values and aggregated terminal offset values.
 6. Thetelecommunication system of claim 5, wherein the processor is programmedto determine the power levels from the measured range data.
 7. Thetelecommunication system of claim 3, wherein the ranging data receivedfrom each of the ranging terminals includes a noise value.
 8. Thetelecommunication system of claim 7, wherein the processor is programmedto determine, using the measured range data, the aggregated interferencefloor values, aggregated terminal offset values, and aggregated noisevalues.